cache_pool.rb

class User
end

class UserChild < User
end

def cache
  @cache ||= {}
end

def get_val(klass)
  return 'x' if klass == Object
end

def pool(klass)
  cache[klass.name] ||= begin
    until val = get_val(klass)
      klass = klass.superclass
      break unless klass <= Object
    end
    cache[klass.name] = val
  end
end

@cache = {}
pool(Object)
puts @cache.inspect # {"Object"=>"x"}

@cache = {}
pool(User)
puts @cache.inspect # {"Object"=>"x", "User"=>"x"}


@cache = {}
pool(UserChild)
puts @cache.inspect # {"Object"=>"x", "UserChild"=>"x"}